1. Field of the Invention
The present invention relates to the transfer of data in a telecommunications system, and more particularly to the routing of data between a network connectable to the telecommunications system and subscriber terminals of the telecommunications system.
2. Description of the Prior Art
In a typical telecommunications system, a subscriber terminal may be located at a subscriber's premises for handling transfer of data to and from that subscriber. One or more lines may be provided from the subscriber terminal for supporting one or more items of telecommunications equipment located at the subscriber's premises. Alternatively, the subscriber terminal may be an integral part of the item of telecommunications equipment. Further, a central terminal may be provided for controlling a number of subscriber terminals, and in particular for managing transfer of data between a subscriber terminal and other components of a telecommunications network.
Each subscriber terminal communicates with the central terminal via a transmission medium, for example copper wires, optical fibres, etc for a wired system, or some form of radio resource for a wireless system. In accordance with known techniques, multiple communication channels may be arranged to utilise the transmission medium for the transmission of signals to and from the subscriber terminal. For example, in a “Code Division Multiple Access” (CDMA) system, signals may be transmitted over the transmission medium on a particular frequency channel, and this frequency channel may be partitioned by applying different orthogonal codes to signals to be transmitted on that frequency channel. Signals to which an orthogonal code has been applied can be considered as being transmitted over a corresponding orthogonal communication channel utilising the particular frequency channel. Similarly, in a “Time Division Multiple Access” (TDMA) system, a particular frequency channel can be partitioned in the time domain, such that a number of different signals can be transmitted in different time slots, the time slots forming multiple communication channels utilising the particular frequency channel. As another example, in a “Frequency Division Multiple Access” (FDMA) system, a band of frequencies may be partitioned to form a number of communication channels at particular frequencies, thereby enabling multiple signals to be transmitted over the transmission medium.
Traditionally, such telecommunications systems have been used to handle voice calls to and from the subscriber terminals, and transport mechanisms have been developed for routing the voice data for such voice calls through the telecommunications system in an efficient manner.
However, nowadays, there is an ever increasing demand for such telecommunications systems to be able to transmit other types of data in addition to, or instead of, voice data. It is possible to route such other types of data using the same transport mechanisms as those provided for handling voice data. However, unlike voice data which is delay sensitive and thus requires continuous operation and relatively constant bit rates, other types of data (e.g. Internet protocol (IP) data) are often bursty, and typically are not delay sensitive, and accordingly the transport mechanisms provided for handling voice data are often not particularly efficient at handling transfer of such other types of data.
As the demand increases for various types of data to be transmitted at higher and higher speeds, it is desirable to provide a transport mechanism which enables more efficient transmission of that data through the telecommunications system.